Effects of rifaximin on bacterial translocation in thioacetamide-induced liver injury in rats

Hepatoprotective Effect of Probiotic Lactic Acid Bacteria on Thioacetamide-Induced Liver Fibrosis in Rats

Hepatic fibrosis is a reversible wound-healing response characterized by the accumulation of extracellular matrix. Probiotics have been used to prevent and treat various disorders. The aim of the present study was to investigate the hepatoprotective effects of probiotic lactic acid bacteria (mixture of Lactobacillus paracasei, Lactobacillus casei, and Weissella confusa) on thioacetamide (TAA)-induced liver fibrosis in rats. Thirty-five male Wistar rats were randomly divided into five groups: (1) control, (2) TAA, (3) TAA+probiotics, (4) TAA+silymarin, and (5) probiotics. Group 1 rats received a standard diet. In groups 2-4, fibrosis was induced by intraperitoneal injection of TAA (200 mg/kg BW) 3 times weekly for 8 consecutive weeks. Group 4 received TAA plus 100 mg/kg BW of silymarin 2 times weekly. Groups 3 and 5 were fed 10⁹ CFU/mL viable microbial cells daily by gavage. The rats were sacrificed after 8 weeks of treatment. Liver tissues were collected immediately and processed for histopathological, lipid peroxidation, and Western blot analyses of TNF-α, TGF-β1, and α-SMA. Blood serum was collected to measure liver enzymes. Rats in the TAA groups suffered from hepatic injury (increased serum enzyme levels, liver inflammation, and increased concentration of TNF-α, TGF-β1, and α-SMA proteins) and extensive liver fibrosis. In contrast, TAA-treated rats receiving probiotics or silymarin had significantly lower serum enzyme levels, less inflammation, and less fibrosis. Liver damage was lower in the TAA+probiotics-treated group. Consumption of a mixture of probiotic lactic acid bacteria attenuates the development of liver fibrosis.

Fiber scaffold bioartificial liver therapy relieves acute liver failure and extrahepatic organ injury in pigs

Rationale: Acute liver failure (ALF) causes severe liver injury and a systemic inflammatory response, leading to multiorgan failure with a high short-term mortality. Bioartificial liver (BAL) therapy is a promising approach that is hampered by the lack of appropriate bioreactors and carriers to retain hepatic cell function and poor understanding of BAL treatment mechanisms in ALF and extrahepatic organ injury. Recently, we used a fiber scaffold bioreactor (FSB) for the high-density, three-dimensional (3D) culture of primary porcine hepatocytes (PPHs) combined with an absorption component to construct a BAL and verified its function in a D-galactosamine (D-gal)-induced ALF porcine model to evaluate its protective effects on the liver and extrahepatic organs. Methods: Male pigs were randomized into standard/supportive therapy (ST), ST+no-cell BAL (ST+Sham BAL) and ST+BAL groups and received treatment 48 h after receiving a D-gal injection. Changes in blood chemistry and clinical symptoms were monitored for 120 h. Tissues and plasma were collected for analysis by pathological examination, immunoblotting, quantitative PCR and immunoassays. Results: PPHs cultured in the FSB obtained sufficient aeration and nutrition for high-density, 3D culture and maintained superior viability and functionality (biosynthesis and detoxification) compared with those cultured in flasks. All the animals developed ALF, acute kidney injury (AKI) and hepatic encephalopathy (HE) 48 h after D-gal infusion and received corresponding therapies. Animals in the BAL group showed markedly improved survival (4/5; 80%) compared with those in the ST+Sham BAL (0/5; p < 0.001) and ST (0/5; p < 0.001) groups. The levels of blood ammonia and biochemical and inflammatory indices were alleviated after BAL treatment. Increased liver regeneration and attenuations in the occurrence and severity of ALF, AKI and HE were observed in the ST+BAL group compared with the ST (p = 0.0009; p = 0.038) and ST+Sham BAL (p = 0.011; p = 0.031) groups. Gut leakage, the plasma endotoxin level, bacterial translocation, and peripheral and neuroinflammation were alleviated in the ST+BAL group compared with those in the other groups. Conclusions: BAL treatment enhanced liver regeneration and alleviated the systemic inflammatory response and extrahepatic organ injury to prolong survival in the ALF model and has potential as a therapeutic approach for ALF patients.

Drug-induced-acute liver failure: A critical appraisal of the thioacetamide model for the study of hepatic encephalopathy

Hepatic encephalopathy (HE) following acute and chronic liver failure is defined as a complex of neuropsychiatric abnormalities, such as discrete personal changes, sleep disorder, forgetfulness, confusion, and decreasing the level of consciousness to coma. The use and design of suitable animal models that represent clinical features and pathological changes of HE are valuable to map the molecular mechanisms that result in HE. Among different types of animal models, thioacetamide (TAA) has been used extensively for the induction of acute liver injury and HE. This agent is not directly hepatotoxic but its metabolites induce liver injury through the induction of oxidative stress and produce systemic inflammation similar to that seen in acute HE patients. In this short review article, we shortly review the most important pathological findings in animal models of acute HE following the administration of TAA.

Translational Approaches with Antioxidant Phytochemicals against Alcohol-Mediated Oxidative Stress, Gut Dysbiosis, Intestinal Barrier Dysfunction, and Fatty Liver Disease

Emerging data demonstrate the important roles of altered gut microbiomes (dysbiosis) in many disease states in the peripheral tissues and the central nervous system. Gut dysbiosis with decreased ratios of Bacteroidetes/Firmicutes and other changes are reported to be caused by many disease states and various environmental factors, such as ethanol (e.g., alcohol drinking), Western-style high-fat diets, high fructose, etc. It is also caused by genetic factors, including genetic polymorphisms and epigenetic changes in different individuals. Gut dysbiosis, impaired intestinal barrier function, and elevated serum endotoxin levels can be observed in human patients and/or experimental rodent models exposed to these factors or with certain disease states. However, gut dysbiosis and leaky gut can be normalized through lifestyle alterations such as increased consumption of healthy diets with various fruits and vegetables containing many different kinds of antioxidant phytochemicals. In this review, we describe the mechanisms of gut dysbiosis, leaky gut, endotoxemia, and fatty liver disease with a specific focus on the alcohol-associated pathways. We also mention translational approaches by discussing the benefits of many antioxidant phytochemicals and/or their metabolites against alcohol-mediated oxidative stress, gut dysbiosis, intestinal barrier dysfunction, and fatty liver disease.

Protective effect of Lactobacillus salivarius Li01 on thioacetamide-induced acute liver injury and hyperammonaemia

The gut microbiota plays pivotal roles in liver disease onset and progression. The protective effects of Lactobacillus salivarius Li01 on liver diseases have been reported. In this study, we aimed to detect the protective effect of L. salivarius Li01 on thioacetamide (TAA)-induced acute liver injury and hyperammonaemia. C57BL/6 mice were separated into three groups and given a gavage of L. salivarius Li01 or phosphate-buffered saline for 7 days. Acute liver injury and hyperammonaemia were induced with an intraperitoneal TAA injection. L. salivarius Li01 decreased mortality and serum transaminase levels and improved histological liver damage caused by TAA. Serum inflammatory cytokine and chemokine and lipopolysaccharide-binding protein (LBP) concentrations, nuclear factor κB (NFκB) pathway activation and macrophage and neutrophil infiltration into the liver were significantly alleviated by L. salivarius Li01. L. salivarius Li01 also reinforced gut barrier and reshaped the perturbed gut microbiota by upregulating Bacteroidetes and Akkermansia richness and downregulating Proteobacteria, Ruminococcaceae_UCG_014 and Helicobacter richness. Plasma and faecal ammonia levels declined noticeably in the Li01 group, accompanied by improvements in cognitive function, neuro-inflammation and relative brain-derived neurotrophic factor (BDNF) gene expression. Our results indicated that L. salivarius Li01 could be considered a potential probiotic in acute liver injury and hepatic encephalopathy (HE).

Dietary α-Lactalbumin protects against thioacetamide-induced liver cirrhosis by maintaining gut-liver axis function in rats

We tested the hypothesis that α-lactalbumin inhibits the disruption of intestinal barrier function and liver cirrhosis by restoring gut-liver axis function in thioacetamide (TAA) -treated rats. Rat diets were supplemented with α-lactalbumin replacing 50% of dietary protein. After consuming α-lactalbumin for one week, rats were intraperitoneally injected with TAA twice a week for 14 weeks. The α-lactalbumin-enriched diet significantly inhibited the elevation of plasma alanine aminotransferase, aspartate aminotransferase, and hyaluronic acids. The supplement significantly reduced plasma lipopolysaccharide levels and increased occludin mRNA level. Hepatic fibrosis and regenerative nodules was developed and intestinal villi were shortened by TAA; α-Lactalbumin attenuated these histopathological changes. These results indicated that α-lactalbumin improved intestinal barrier function, suppressing endotoxin levels. These data also suggested that α-lactalbumin ameliorated the impairment of the gut-liver axis by TAA, inhibiting the development of liver cirrhosis.

Norfloxacin is more effective than Rifaximin in avoiding bacterial translocation in an animal model of cirrhosis

BACKGROUND & AIMS

Norfloxacin administration is useful in preventing bacterial infections in cirrhosis but associated to the generation of resistant species. Rifaximin is known to reach high concentrations in the intestinal lumen without generating relevant resistance in the intestinal flora. Our aim was to compare the effect of Norfloxacin and Rifaximin on intestinal flora composition, bacterial translocation and survival in cirrhotic rats.

METHODS

Cirrhosis was induced in rats by oral administration of CCl₄ . Animals were divided into three groups: only CCl₄ (group I, n = 10); CCl₄ + Norfloxacin (group II, n = 17) and CCl₄ + Rifaximin (group III, n = 14). Gut bacterial composition, bacterial translocation and cytokine levels were measured.

RESULTS

Forty-one rats were finally included. The incidence of viable and non-viable bacterial translocation was significantly reduced in animals receiving Norfloxacin; Rifaximin also decreased the incidence of viable and non-viable bacterial translocation, but did not reach statistical significance. Serum TNF-α levels were significantly lower in antibiotic groups. Norfloxacin modified intestinal microbiota, depleting significantly more pathobionts than Rifaximin.

CONCLUSION

Norfloxacin is more effective than Rifaximin in preventing bacterial translocation in rats with cirrhosis probably because of its capacity to reduce pathobionts from intestinal microbiota.

Toll-Like Receptor 4-Independent Carbon Tetrachloride-Induced Fibrosis and Lipopolysaccharide-Induced Acute Liver Injury in Mice: Role of Hepatic Stellate Cells

Gram-negative bacterial endotoxin lipopolysaccharide (LPS) is implicated in acute and chronic liver injury; its effects are mediated predominantly via the membrane receptor Toll-like receptor 4 (TLR4). However, TLR4-independent effects of LPS may play important role in hepatic pathophysiology. We investigated carbon tetrachloride (CCl4)-induced fibrosis and LPS-induced acute liver injury in wild-type (WT) and B6.B10ScN-Tlr4lps-del/JthJ [TLR4-knockout (KO)] mice. Effects of LPS on fibrogenic hepatic stellate cells (HSCs) from WT and TLR4-KO mice were assessed in vitro. CCl4 produced similar fibrosis and necroinflammation and increased the mRNA and protein expression of cytokines and chemokines in WT and TLR4-KO mice. However, circulating LPS concentration did not increase in CCl4-treated mice. Interestingly, LPS down-modulated α-smooth muscle actin (activated HSC marker) and collagen 1 in both WT and TLR4-KO HSCs. LPS induced similar activation of NF-κB, and stimulated the expression of cytokines and chemokines in WT and TLR4-KO HSCs. Finally, LPS caused similar inflammation and injury in previously untreated WT and TLR4-KO mice. The results provide evidence of the TLR4/LPS-independent mechanisms of liver fibrosis and also indicate that TLR4 is not entirely critical to LPS-induced acute liver injury. The results further indicate that LPS signaling in activated HSCs might be a mechanism of limiting liver fibrosis.

Small bowel protection against NSAID-injury in rats: Effect of rifaximin, a poorly absorbed, GI targeted, antibiotic

Nonsteroidal anti-inflammatory drugs, besides exerting detrimental effects on the upper digestive tract, can also damage the small and large intestine. Although the underlying mechanisms remain unclear, there is evidence that enteric bacteria play a pivotal role. The present study examined the enteroprotective effects of a delayed-release formulation of rifaximin-EIR (R-EIR, 50mg/kg BID, i.g.), a poorly absorbed antibiotic with a broad spectrum of antibacterial activity, in a rat model of enteropathy induced by indomethacin (IND, 1.5mg/kg BID for 14 days) administration. R-EIR was administered starting 7 days before or in concomitance with IND administration. At the end of treatments, blood samples were collected to evaluate hemoglobin (Hb) concentration (as an index of digestive bleeding). Small intestine was processed for: (1) histological assessment of intestinal damage (percentage length of lesions over the total length examined); (2) assay of tissue myeloperoxidase (MPO) and TNF levels, as markers of inflammation; (3) assay of tissue malondialdehyde (MDA) and protein carbonyl concentrations, as an index of lipid and protein peroxidation, respectively; (4) evaluation of the major bacterial phyla. IND significantly decreased Hb levels, this effect being significantly blunted by R-EIR. IND also induced the occurrence of lesions in the jejunum and ileum. In both intestinal regions, R-EIR significantly reduced the percentage of lesions, as compared with rats receiving IND alone. Either the markers of inflammation and tissue peroxidation were significantly increased in jejunum and ileum from IND-treated rats. However, in rats treated with R-EIR, these parameters were not significantly different from those observed in controls. R-EIR was also able to counterbalance the increase in Proteobacteria and Firmicutes abundance induced by INDO. To summarize, R-EIR treatment significantly prevents IND-induced intestinal damage, this enteroprotective effect being associated with a decrease in tissue inflammation, oxidative stress and digestive bleeding as well as reversal of NSAID-induced alterations in bacterial population.

Effects of Lycium barbarum on bacterial translocation in thioacetamide-induced liver injury in rats

Background and study aim:

The aim of the present study was to investigate the effects of Lycium barbarum (LB) on bacterial translocation (BT) frequency in thioacetamide (TAA)-induced liver injury in rats.

Materials and methods:

Group 1 was the control. In group 2 (TAA), rats received TAA daily for 3 days. In group 3 (TAA+LB), Lycium barbarum was administered orally 25 mg/kg for 21 days prior to the first TAA injection. In group 4 (LB), rats received only Lycium barbarum.

Results:

In our study, Lycium barbarum treatment did not attenuate liver damage. Lycium barbarum treatment decreased ileal E. coli counts and intestinal damage but it did not alter BT frequency.

Conclusions:

In conclusion, the effects of Lycium barbarum on BT may be related to ongoing severe liver damage in this model.

Impact of rifaximin on the frequency and characteristics of spontaneous bacterial peritonitis in patients with liver cirrhosis and ascites

Background

Rifaximin is a non-absorbable antibiotic used to prevent relapses of hepatic encephalopathy which may also be a candidate for prophylaxis of spontaneous bacterial peritonitis (SBP).

Aim

To detect the impact of rifaximin on the occurrence and characteristics of SBP.

Methods

We prospectively studied all hospitalized patients that underwent a diagnostic paracentesis in our department from March 2012 to April 2013 for SBP and recorded all clinical data including type of SBP prophylaxis, prior use of rifaximin, concomitant complications of cirrhosis, as well as laboratory results and bacteriological findings. Patients were divided into the following three groups: no antibiotic prophylaxis, prophylaxis with rifaximin or with systemically absorbed antibiotic prophylaxis.

Results

Our study cohort comprised 152 patients with advanced liver cirrhosis, 32 of whom developed SBP during the study period. As expected, our study groups differed regarding a history of hepatic encephalopathy and SBP before inclusion into the study. None of the 17 patients on systemic antibiotic prophylaxis developed SBP while 8/27 patients on rifaximin and 24/108 without prophylaxis had SBP (p = 0.02 and p = 0.04 versus systemic antibiotics, respectively). In general, episodes of SBP were similar for patients treated with rifaximin and those without any prophylaxis. However, Escherichia coli and enterococci were dominant in the ascites of patients without any prophylaxis, while mostly klebsiella species were recovered from the ascites samples in the rifaximin group.

Conclusion

Rifaximin pretreatment did not lead to a reduction of SBP occurrence in hospitalized patients with advanced liver disease. However, the bacterial species causing SBP were changed by rifaximin.